Vehicle dumping apparatus



May 12, 1942. E. B. THOMPSON VEHICLE DUMPING APPARATUS Original FiledJune 15, 1936 3 Sheets-Sheet l May 12-, 1942. as. THOMPSON VEHICLEDUMPING APPARATUS Original Filed June l5 1936 3 Sheets-Sheet 2 Ma 12,1942. E. B. THOMPSON VEHICLE DUMPINQ APPARATUS Original Filed June is,1936 5 Sheets-Sheet s Patented May 12, 1942 2,282,621 VEHICLE DUMPINGAPPARATUS Elmer B. Thompson, Des Moines, Iowa, assignor to Globe HoistCompany, Des Moines, Iowa, a

corporation of Iowa Substituted for abandoned application Serial No.85,258, June 15, 1936. This application October 2, 1939, Serial No.297,527

11 Claims.

In the art of vehicle dumping, such, for instance, as dumping grain atgrain elevators, it is desirable that the grain be dumped at apredetermined dumping point. In former years substantially all of suchgrain or the like wasdelivered to the elevator in wagons ofsubstantially uniform length and having substantially the same distancebetween the rear axle and the rear of the wagon box, and under suchcircumstances it was only necessary to provide a single means forengaging and elevating the front wheels' At the present time grain andother products are brought to grain elevators in vehicles of variouskinds, including horse-drawn wagons, automobile trucks and trailertrucks, the latter having an axle at the front of the cab, another axleat the rear of the cab, and a third axle at the rear of the trailerbody, and there is a limited pivotal connection vertically between thetruck and the front of the trailer body. Hence, it

would not be practicable to dump the trailer-- truck by elevating thefront wheels only of the truck or the rear wheels only of the truck.

The object of my invention is to provide a lift device of this characterof simple, durable and inexpensive construction so constructed andarranged that it may be readily, quickly and easily adapted for use inconnection with vehicles of the classes before mentioned, and quicklyand easily moved to dumping position to accurately spot the contents ofthe body at the desired dumping place.

More specifically, it is my object to provide a dumping apparatus ofthis class which may be readily, quickly andeasily adjusted to positionfor dumping a wagon without unhitching the horses therefrom, or dumpinga trailer truck and keeping the three axles of the trailer trucksubstantially in alinement during the raising and lowering movement, andalso for permitting the two independent lift devices to move toward andfrom each other and toward and from the rear axle of the vehicle duringsuch raising and lowering movement.

More specifically, it is my object to provide two independent liftingdevices for the frontv and rear wheels of a trailer truck vehicle to bemoved upwardly and downwardly during a dumping movement, and in whichthe lift device for the front axle will automatically be moved fasterthan the lift device for the rear axle thereof, so that the cab willmaintain its aligned position relative to the truck body during suchmovement to and from said dumpin position- More specifically, it is myobject 'to provide "a Gil device of this class in which the upward limitof the movement of the wheel-engaging platform may be automaticallystopped at several predetermined positions.

A further object is to provide means whereby the lift device may beautomatically locked againstlongitudinal movement during the time thatthe motor is at rest, and be automatically released for longitudinalmovement when the -motor is running, and further in this connectionprovidea gripping device which, when thus released, will prevent tiltingmovements of the upright supports for the lift in a direction longitudinally of the lift.

A further object is to provide means for automatically stopping themotor during this elevating movement when the vehicle being elevatedreaches its upward limit of movement, and further in this connection toprovide means for jointly operating the gripping devices of both of thelift devices.

In the accompanying drawings Figure 1 shows a side view of'my improvedlift with a trailer truck mounted thereon in dumping position;

Figure 2 shows an enlarged detail side view of a part of the lift frameillustrating the gearing mechanism for raising and lowering thewheel-supporting platform, the gear case being shown in section;

Figure 3 shows a similar view of a portion of this gearing mechanism toillustrate the difference in the gear ratio between the two gears of thetwo lift devices;

Figure 4 shows a detail side elevation of a portion of two adjacent liftdevices, and illustrating a modified means for operatively connectingthe gearing devices of the two lift devices;

Figure 5 shows a vertical transverse sectional view of my improved lift,partly in section and taken on the line 5-5 of Figure 1;

Figure 6 shows an enlarged detail side elevationillustrating the controllever for the motor and the means for operating the rail-gripping deviceand also the means for stopping the motor ,at various points throughoutthe up and down movement of the lift;

Figure 7 shows a horizontal sectional view '1 taken on the line l--'l ofFigure 5 and Figure 8'illustrates diagrammatically the electric circuitfor the two motors;

Figure 9 illustrates my modified form of clamping device;

Figure 10 is a detail sectional the line llL-l 0 of Figure 9.

Referring to the accompanying drawings. it

view taken on will be seen that there are two independent lift devices,each of which comprises a base H! extended longitudinally of the liftand having grooved supporting wheels II at its forward and rear ends.These grooved supporting wheels H are mounted upon T rails I2, andprojected upwardly from the central portion of the base I is asupporting member I3. This supporting member is provided with twoupright racks I4, one at the front edge and the other at the rear edge.A similar base and upright device is provided for another rail on theopposite side of the roadway for the vehicles. Slidingly mounted uponthese uprights I 3 is a vehicle wheel-engaging and supporting platformcomprising side members l5 and cross members I6, spaced apart from eachother in such position that vehicle wheels may be driven upon thisplatform andthe wheels will be supported against forward or rearwardmovement relative to the platform by said cross members It. This slidingplatform also holds the upright racks properly spaced apart and preventsthem from tilting toward or from each other. In some cases I may add anelevated track rail Ila secured to a suitable support, and groovedwheels I 11) on the taller upright rack for preventing tiltingmovements.

Mounted in the wheel-supporting platform and extended below the crosspieces l6 are two shafts I1, each having a pinion I 8 on each end andmeshing with their respective racks l4.

For the purpose of driving the shafts I! to thereby raise and lower thepinions I8 I have provided on the wheel-engaging and supporting platformat one end a gear case l9. Into this gear case the two shafts I! areextended, and fixed to said shafts'within the gear case are two idlergear wheel 20 operatively connected through the idler gear wheels 2!,and one of these gear Wheels 2| is in mesh with the gear wheel 22 fixedto the shaft 23 which is fixed to a pulley 24 connected by a'belt 25with a pulley 26 on the shaft of the electric motor 21, which motor isalso carried by the wheel-supporting and elevating frame.

By means of the construction heretofore described it will be seen thatthe lift device may be moved toward and from the dumping spot readilyand easily upon the wheels II on the rails I 2, to position for engagingthe wheels of a vehicle with the rear of the vehicle at the properposition relative to the dumping spot. Then when the electric motor isturned the gears l8, operating on the racks l4, will raise and lower thewheel-supporting platform.

For the purpose of adapting my vehicle dumping apparatus for use inconnection with trailer trucks of the class described, I provide asecond lift device in all respects corresponding to that portion of thefirst lift device previously described, except that the gear wheel 22 islarger than the corresponding gear wheel on the first mentioned liftdevice, as illustrated in Figure 3, so that when the two electric motorsare driven at the same speed, the wheel-engaging and supporting platformof the last mentioned lift will be moved upwardly and downwardly fasterthan the corresponding part of the first mentioned lift device, andthese gears are so proportioned that the lift device for the frontwheelsof a trailer faster than the lift device for the rear wheels ofthe trailer truck cab, so-that the. cab will maintain substantially itsnormal position relative to 5 a truck body during all positions of itselevating and lowering movement.

For the purpose of at times locking the wheel supports of both liftdevices to the rails to prevent longitudinal movement, I have providedthe following mechanism: Mounted upon the frame member If! is a pair'ofpivoted gripping jaws 28 to pass around the top of the rail l2 andengage the sides of the rail below the top. The outward movement ofthese gripping jaws is limited by a bolt 29 passed through both jaws,and this outward limit is only suflicient to permit the jaws to slidelongitudinally relative to the rail, but not upwardly, so that at alltimes these gripping jaws prevent tilting movements of the upper ends ofthe frame members l3 forwardly or rearwardly relative to the liftdevice. By the use of the term locking means as used in the accompanyingclaims, I mean any device which will hold the frames againstlongitudinal movement.

For; the purpose of applying pressure to the gripping jaws to move themto gripping position, I have provided an upright shaft 30 pivotallysupported at its. lower end in the frame I0 and having a handle 3| bywhich it may be manually rotated. At the lower end of this shaft is acam 32- positioned. adjacent one of the gripping jaws and so constructedthat when the handl 3| is turned in one direction, the cam will forcethe adjacent gripping jaw into gripping contact with the rail.

For the purpose of automatically operating the gripping device of theend lift device in unison with that of the intermediate gripping device,I have provided on the shaft 30 a beveled pinion 33 inmesh with abeveled pinion 34, and a square tubular shaft 35' extended forwardlyhorizontally. A. square shaft 36 is telescopically mounted in thesquaretubular shaft 35; On the other end of the shaft 36 is a beveled pinion31in mesh with the beveled pinion 38 on the cam rod 39 of the forwardgripping device. By this means the two gripping devices are operated inunison and the lift dew'ces may be moved toward and from each other. Ihave also provided a locking device to hold the upper end of the tallerlift to the elevated rail, for which purpose I provide a gripping devicesimilar to the one I have described for the lower end of the rack andindicated generally by the reference symbol 32a, and connected to saidlower locking device by a shaft 32b.

For the purpose of controlling the operation of the two electric motorsand for limiting the upward and downwardmovements of the wheel-'supporting platforms, I have provided the following mechanism: Referencenumeral 40 indicates generally a switch device for the motor 21, and itis provided with an arm 4|. This arm is connected by a link 42 with amanually controlled lever 43, pivoted at 43 and this lever has fixed toit two downwardly extended walls 44 spaced apart with the rod .30extended between them. This rod 30 is flat at 30*, as clearly shown inFigure 6, and when in the position shown in Figure 6 the lever 43 may bemoved far enough to throw the arm 4| to position for stopping the motoror causing it to rotate in either direction. When, however, the rod 30is turned to a position at right angles to that shown in Fig. 6, thelever 43 cannot be moved, hence, the motor cannot be operated.

For the purpose of normally holding the fiat rod 3|] in the position forlocking th switch I have provided springs 45 connected to the upper endthereof for yieldingly holding the flat rod amass 1 30 in said position.This rail-locking device is normally held in its locking position by thesprings 45. When, however, it is desired to release it, then theoperator manually moves the lever 3! to releasing position.

It is desirable that the motor cannot be started to move in eitherdirection so long as the gripping device is in locked position, hence,when the gripping device is locked,'the flat rod 30 engages both of thewalls 44 and prevents movement of the lever 43, hence, before this lever43 can be moved to start the motor in either direction the operator mustmanually move the lever 3| from the position shown in Fig. 5, to theposition shown in Figure 6, whereupon the lever 43 may be moved to startthe motor, and during the movement of the motor in either directionit'is necessary that the lift bepermitted to move longitudinally uponthe track.

For the purpose of automatically stopping the motor when thewheel-engaging and supporting platform has reached any predeterminedposition of its up and down movement, I have prothe operation is asfollowsiiWhen the vehicle is to be driven on to thewheel-engaging andsupporting platform itis desirablefto havethe lift device locked tothejrails to prevent longitudinal movement thereon, and this isaccomplished automatically, as before described. When in this positionthe electricmotor cannot be started because of the fiat rod 30 engagingthe walls 44 of the switch controlling lever 43, so that before startingthe motor, the operator must manually release the gripping device, thenthe switch controlling lever 43 is moved to position for causing themotor to turn in a direction for raising the vided the followingmechanism: 46 indicates a shaft mounted in the upright frame, as shownin Figure 6, and this shaft is provided with a handle 41 by which it maybe rotated. Mounted on the lower portion of this rod is a disc 48, andat the upper portion there are a number of outwardly projecting pins 49extended at different angles relative to the rod. When the lever 43 ismoved downwardly with the wheel-engaging and supporting platform it willstrike upon the disc 48, no matter in what position the shaft 46 hasbeen turned, and as the lever 43 moves upwardly with the wheelsupporting platform it will strike that particular one of the pins 49which is projected outwardly into the path of the lever 43, but will notengage the other pins. Hence, by this means the operator may, by placingthe handle 41 in various positions, determine the point of elevation atwhich the lift will automatically stop.

I have also provided a means for automatically stopping the upwardmovement of both of the lift devices when the vehicle carried therebyreaches its upward limit of movement. I accomplish that by means of apivoted lever 5llsupported above a vehicle on the lift, which lever isconnected by a switch lever 5| included in the circuit for the motor,and these parts are so arranged that when the lever 59 is movedupwardly, the circuit is opened.

In Figure 8 I have illustrated diagrammatically I a preferred form forthe electric circuit. This illustrates the two electric motors ofreversible motor type, included in the same circuit in which theswitches 5| and 40 are also included.

In the modified form illustrated in Figure 4 I have shown a means forutilizing a single motor on one of the lifts and driving the gear on theother lift from the said motor. This means comprises a beveled pinion 52connected with the shaft 23 of the gear mechanism for one of the lifts,which beveled pinion is in mesh with the beveled pinion 53 on a hollowsquared shaft 54;

the squared shaft 55.is telescopically connected with the shaft 54 andhas a pinion 56 on its end in mesh with the pinion 51 on thecorresponding shaft 23 of the gearing device of the other lift device.

In practical operation, and assuming that the vehicle to be dumped is ahorse-drawn wagon, then only the intermediate lift device is used, and

lift, and during this raising movement the lift is free to movelongitudinally upon the rail. If the operator should neglect to throwthe switch 43 when the lift reaches its elevated position, this would beautomatically accomplished by having the lever 43 engage one of the pins49. Wherr the lift is in its elevated position the operator may, ifdesired, lock the gripping device to the rails, and then before thedownward movement can be commenced, the gripping device will again haveto be released before the motor can be operated in a direction to lowerthe lift, and the lowering movement is again automatically stopped bythe engagement of the lever 43 with the disc 48, and in the event thatthe top of the vehicle should approach the danger point when beingelevated, and before the upward movement is automatically stopped by thelever 43, then the top of the vehicle will engage the lever 55 .andautomatically break the circuit and stop the motor, Whether the grippingdevice is locked to the rail or in its released position, it will at alltimes serve to prevent the wheel-supportin platform of the lift fromtilting forwardly or rear- ..wardly because these gripping jawsengage-the under surface of the head of the T rail.

In the event that the vehicle to be elevated is a trailer truck or thelike, then-the first lift device is moved to position where it willengage the 'front wheels of the trailer truck and the second lift devicemoved to position where it will engage the intermediate wheels of thetrailer truck, and both of these lift devices -may be moved forwardlyand rearwardly upon the rails until they are in approximately the rightposition, then they are locked to the rails by the gripping device andthe truck driven on to both of the wheel-receiving and supportingplatforms. Then the gripping device must again be released before themotor can be started to elevate. During this elevation these two liftdevices will move toward each other and, hence, the wheel-supportingbases must be free for such movement during said elevation, and also,when lowering, the forward one will move away from "the intermediateone.

I have found in practice that the two motors connected on the samecircuit will rotate at substantially the same speed, and by providinggear;

- of the operator, and I have found that with this device I canaccommodate all of the various sizes and types of vehicles which are inuse at the present time for the purposes for which my invention isdesigned. a

I have found that with my improvement considerable expense is avoided inthe installation of the apparatus. With my improvement it is onlynecessary to secure the two rails to the trackway or elevator, as thecase may be, whereas, with devices of this character previously used itwas necessary to install part, or'most, of the apparatus under theroadway or elevator.

In modern elevators it is customary to have numerous dumping receptaclesfor different kinds of grain or products.

easily moved along the rails to bring the rear of the vehicle to anyselected one of a series of dumping spots.

In Figures 9 and 10 I have illustrated a modified form of rail gripperand means for automatically operating the same. In the employment ofthis modified form I eliminate the shafts 39, 321), the shafts 35 and36, together with the associated bevel gears and the gripper members 32;Instead of the grippers 32 I have provided in the members ID a shaft 58having mounted thereto one end of a lever 59.. Pivotally connected tothe central portion of the lever 59 is a yoke or gripping device 60having at its lower ends inwardly turned portions 6| designed to engagethe under surface of the ball of the rail l2 when the yoke is at anelevated position of movement, and to free said rail when in a loweredposition of movement, to thereby provide means whereby the rail will begripped and the frame Ill held against longitudinal movement when thefree end of the lever 59 is elevated.

For elevating and lowering the lever 59 Ihave provided in each of the Tbars supporting the racks 14, in place of said racks, a slidably mountedrack bar 62, limited against upward movement by means of an outwardlyextending lug 63 and against downward movement by means of a lug 64, therack BZ'being shorter than the distance between the lugs 63 and 64, sothat said rack bars are permitted to move vertically relative to theframe members l3, the said rack bars being in mesh with the pinions H3.The lower end of one of the frame members I3 is provided with a notch 65for receiving the bracket 66, one end of which is fixed to the rack 62and the other end projecting laterally to a position over the free endof the lever 59. Supported in the bracket 66 is a rod 61 having itslower end threaded and passing through said lever 59 and adapted tosupport springs 68 above and below said lever, said springs beingsecured in position by nuts 69. {The rack bar 62 is also provided with alaterally extending pin I designed to engage the lower. edge of thelever 43 when the lift is at or near its lower position of movement.

From the above construction it will be seen 'that if the pinions l8 arerotated in one direction, then the lift will be elevated in the mannerbefore described. In like manner, if the pinions I8 are rotated in theopposite direction, then the lift will be lowered until the members l6engage the floor on which the lift is mounted. Further rotation of thesaid pinions I8 will then cause the rack 62 to be elevated, and with itthe pin 10, which will at that time engage the under surface of thelever 43, causing said lever to be elevated and the motor 21 to becomeinoperative. In this connection it should be borne in mind that thediscs 48 may be eliminated and the With my improved appa- V ratus theentire lift device may be readily and pin 10 used to perform the samefunction. This upward movement of the racks 62 will cause the lever 59,to also be elevated and the gripper set to lock the trucks againstlongitudinal movement.

In the gripping arrangement before described the grippers were set andreleased by a handactuated lever, and it was necessary to provide meansfor properly connecting the grippers of both of the trucks, while in themodified form each of the trucks is provided with an independent andautomatically-operated gripping mechanism, so arranged that at all timeswhen the lifts are down the'grippers are set.

This application is a substitute for applicants former application filedJune 15, 1936, Serial No. 85,258, for a Vehicle dumping apparatus, whichbecame forfeited by non-payment ofthe final government fee.

I claim as my invention:

1. In a device of the class described, the combination of a lift frame,grooved supporting wheels, one extended rearwardly .and one forwardlyfrom the frame, a T rail fixed in position and having said groovedwheels mounted thereon, a pair of gripping jaws carried by the frame andpositioned one on each side of the rail, means for limiting the outwardmovement of the jaws relative to the rail so that at all times the jawswill extend under the head of the rail and limit the upward movement ofthe jaws relative to the rail, a, manually operable cam carried by theframe for moving one of the jaws to gripping position on the rail, anelectric motor driven mechanism carried .by the frame'for raising andlowering a vehicle, a manually operable switch device for the motor,said switch device having two spaced apart walls carried thereby, a fiatrod connected to said. cam and extended between said spaced apart wallson said switch device, said parts being so arranged and proportionedthat when the flat rod is in position parallel with the sides of saidflat rod the said switch device may be moved, and when said fiat rod isat right angles to said walls, the switch device will be held in itsinoperative position.

2. In a device of the class described, the combination of a lift frame,grooved supporting wheels, one extended rearwardly and one forwardlyfrom the frame, a T rail fixed in position and having said groovedwheels mounted thereon, a pair of gripping jaws carried by the frame andpositioned one on each side of the rail, means for limiting the outwardmovement of the jaws relative tothe rail so that at all times the jawswill extend under the head of the rail and limit the upward movement ofthe jaws relative to the rail, a manually operable cam carried by theframe for moving one of the jaws togripping position on the rail, anelectric motor driven mechanism carried by the frame for raising andlowering a vehicle, a manually operable switch device for the motor,said switch device having two spaced apart walls carried thereby, a fiatrodconnected to said cam and extended between said spaced apart walls onsaid switch device, said parts being so arranged and proportioned thatwhen the flat rod is in position parallel with the sides of said fiatrod the said switch device may be moved, and when said fiat rod is atright angles to said walls, the switch device will be held in itsinoperative'position, and spring actuated means for normally holdingsaid cam in its withdrawn position.

3. In a device of the class described, the combination of a lift frame,.a vehicle supporting frame vertically slidable upon the lift frame, anelectric motor carried by the vehicle supporting frame, a switch devicefor the electric motor including a projecting arm by which the switchmay be operated, an upright rod rotatably supported upon the lift frame,a handle on the rod for turning it to different positions of its rotarymovement, a, series of stops fixed to the rod at different elevationsand projected outwardly therefrom at different angles, and so arrangedrelative to the said arm thatany selected one of said stops may beplaced in the path of the arm and when engaged by the arm will move theswitch to position forstopping the motor, and a disc-shaped stop deviceat the lower end of the rod to be engaged by the said arm when at itslower limit of movement and when the rod is in any of its adjustedpositions, to thereby move said arm to position for stopping the motor.

4. A vehicle dumping apparatus, comprising a lift device for engagingand elevating the front portion of a vehicle, a second lift device forengaging and elevating the same vehicle at a point between the ends ofthe vehicle, means for raising and lowering the front lift at one rateof speed and the other lift at a less rate of speed and whereby thevehicle engaging portions of both lifts will hold the front portions ofthe vehicle substantially in line with the rear portion of the vehiclewhen in any position of its movements to and from said dumping position,means for movably supporting each of said lifts for permitting them tomove horizontally toward and from each other and toward and from thedumping point for the vehicle during a vehicle dumping movement, alocking device for each of said devices to prevent said horizontalmovement, means for jointly operating said locking devices, a manuallyoperable lever for controlling the means for raising and lowering thelift devices, spring actuated means for normally holding said lockingdevices in position for preventing movement of said lever, and manuallyoperable means for moving said locking devices to position forpermitting movement of said lever.

5. The combination of a vehicle lift frame, means for movably supportingit, a rail extended longitudinally relative to the path of movement ofthe lift, an automatic gripping device carried by the lift frame forgripping the rail, means carried by the lift frame for raising andlowering the lift, a manually operable element carried by the lift framefor controlling the means for raising and lowering the lift, saidelement when in one position causing the raising and lowering mechanismto operate, and when in another position causing the raising andlowering mechanism to be inoperative, manually operable means forreleasing said gripping device, and a locking device for holding saidelement in an inoperative position, said locking device and saidgripping device being operatively connected so that when the grippingdevice is in gripping position the said element is held in inoperativeposition.

6. The combination of a vehicle lift frame, means for movably supportingit, a rail extended longitudinally relative to the path of movement ofthe lift frame, a gripping device carried by the lift frame for grippingthe rail, means carried by the lift frame for raising and lowering thelift, a manually operable element carried by the lift frame forcontrolling the means for raising and lowering the lift, said elementwhen in one position causing the raising and lowering mechanismtooperate, and when in another position causing the raising and loweringmechanism to be inoperative, a locking device forholding said element inits inoperative position, and means operatively connected with saidgripping device and with said locking device for holding jointly thegripping device and the locking device in an inoperative position, orjointly holding both in released position.

'7. The combination of a vehicle lift frame,

means for movably supporting it, a rail extended longitudinally relativeto thepath of movement of the lift frame, a gripping device carried bythelift frame for gripping the rail, means carried by the lift frame forraisingand lowering the lift, a manually operable element carried by thelift framefor controlling the means for raisingand lowering the lift,said element when in one position causing the raising and loweringmecha-- nism to operate, and when in another position causing theraising and lowering mechanism to be inoperative, a locking device forholding said element in its inoperative position, means operativelyconnected with said gripping device and with said locking device forholding jointly the gripping device and the locking device in aninoperative position, or jointly holding both in released position, asecond similar lift frame equipped with a similar rail gripping device,and an extensible power transmitting connection between said grippingdevices whereby the said second gripping device is operated in unisonwith the first when said lift frames are in any position of theirmovement relative to each other.

8. In a device of the class described, the combination of a vehicle liftframe, a lift carried by the frame, two supporting wheels for the framespaced apart one in advance of the other, a rail upon which said wheelsare mounted, an antitilting device carried by the frame between saidwheels to cooperate with the rail to prevent upward movement of theframe relative to the rail, a rail gripping member carried by the frame,and means for automatically actuating it to release the rail when thelift is being raised or lowered and to automatically grip the rail whenthe lift is stationary. r

9. Ina device of the class described, the combination of a vehicle liftframe, a lift carried by v the frame, two supporting wheels for theframe spaced apart, one in advance of the other, a rail upon which saidwheels are mounted, an antitilting device carried by the frame betweensaid wheels to cooperate with the rail to prevent upward movement of theframe relative to the rail, including a rail-gripping member carried bythe frame, and means actuated'upon by elevating and lowering the liftfor clamping or releasing the gripping means automatically to and fromthe rail when the lift is near its lower position of movement. I

10. An apparatus for dumping vehicles of the class having a truck and atrailer, comprising a platform to receive and support truck wheels, asecond platform to receive and support the front wheels of a trailer,means for jointly elevating and lowering said platforms to and fromdumping position of the trailer, said means including mechanism formoving the truck platform faster than the trailer platform to maintainthe truck and trailer in substantially longitudinal alignment during adumping movement, means for supporting said platform for freelongitudinal movement for permitting both platforms to move in arcscentered at the axis of the rear wheels of a trailer being dumped, andmeans actuated by the final trailer platform to maintain the truck andtrailer 15 lowering movement and the initial elevating in substantiallylongitudinal alignment during a dumping movement means for supportingsaid platform for free longitudinal movement for permitting bothplatforms to move in arcs centered at the axis'of the rear wheels of atrailer being dumped, means actuated by the final lowering movement andthe initial elevating movement of said lifts for locking and unlockingsaid liftsupporting means against longitudinal movement automaticallywhen the lifts are at their lowered position, and means actuated by saidlowerin movement for automatically causing said prime mover to becomeinoperative.

ELMER B. THO-NEPSON.

